IET GenRad 1404 Series Primary Standard Capacitors

IET GenRad 1404 Series Primary Standard Capacitors

The IET GenRad 1404 series Primary Standard Capacitors are the standard choice in metrology laboratories, and are still used today by NMIs around the world.

These capacitors have been designed as primary reference standards of capacitance with which working standards can be compared. IET’s 1620A and 1621 Precision Capacitance Measuring Systems are particularly well suited for this purpose and can be conveniently used to accurately calibrate a wide range of working standards in terms of a 1404 Reference Standard Capacitor.
IET has expanded on the GenRad 1404 Series with the New 1404-5nF and 1404-10nF Standard Capacitors. These build on the outstanding time tested performance and stability features of the classical design of the original GenRad 1404’s. Model 1404-A 10 nF and 1404-C 10 pF

In combination with an accurately known external resistor, this capacitor also becomes a standard of dissipation factor.

All critical parts of the plate assembly are made of invar for stability and low temperature coefficient. After heat cycling and adjustment the assembly is mounted in a heavy brass container, which after evacuation, is filled with dry nitrogen under pressure slightly above atmospheric and sealed. The container is mounted on an aluminum panel and protected by an outer aluminum case. Each capacitor is subjected to a series of temperature cycles to determine hysteresis and temperature coefficients and to stabilize the capacitance.

Two locking bnc coaxial connectors are used as terminals (other connectors such as 874 type are available as options). The outer shell of one is connected to the case, but the outer shell of the other is left unconnected to permit the capacitor to be used with an external resistor as a dissipation factor standard.